Adult Epstein–Barr virus encephalitis: a retrospective case report series with metagenomic next-generation sequencing-based diagnosis

Background EBV encephalitis is uncommon in adults, and its diagnosis and management remain challenging, particularly in patients with underlying medical conditions. Methods We retrospectively analyzed seven adult patients with EBV encephalitis confirmed through cerebrospinal fluid (CSF) metagenomic next-generation sequencing (mNGS) between December 2021 and January 2024. Results Six patients (86%) were female, with a median age of 59 years. Five patients had significant underlying conditions, including malignancies ( n = 2), systemic lupus erythematosus ( n = 1), and EBV-associated hemophagocytic lymphohistiocytosis (HLH, n = 2). Common clinical presentations included fever (86%), impaired consciousness (86%), neck stiffness (57%), headache (43%), and decreased muscle strength (43%). CSF analysis revealed elevated protein levels (57%) and leukocytosis (71%). Magnetic resonance imaging (MRI) identified encephalitis-associated lesions in three of six patients (50%), whereas computed tomography (CT) was largely unremarkable. All patients received antiviral therapy, and five additionally received corticosteroids. Three patients recovered, whereas four died, with all deaths occurring in patients with concurrent malignancies or HLH. Conclusion MRI is the preferred imaging modality for suspected encephalitis, and CSF-mNGS is an essential pathogen detection assay. Underlying conditions such as malignancies and HLH are associated with poor clinical outcomes.